US9911456B2 - Spindle motor and disk drive apparatus - Google Patents

Spindle motor and disk drive apparatus Download PDF

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Publication number
US9911456B2
US9911456B2 US15/438,953 US201715438953A US9911456B2 US 9911456 B2 US9911456 B2 US 9911456B2 US 201715438953 A US201715438953 A US 201715438953A US 9911456 B2 US9911456 B2 US 9911456B2
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United States
Prior art keywords
cylindrical portion
spindle motor
bearing mechanism
communicating hole
base member
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Expired - Fee Related
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US15/438,953
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English (en)
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US20170249968A1 (en
Inventor
Tomohiro YONEDA
Takeshi Ohiro
Takayuki Ishino
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Nidec Corp
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Nidec Corp
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Assigned to NIDEC CORPORATION reassignment NIDEC CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ISHINO, TAKAYUKI, OHIRO, TAKESHI, YONEDA, TOMOHIRO
Publication of US20170249968A1 publication Critical patent/US20170249968A1/en
Priority to US15/828,474 priority Critical patent/US10102876B2/en
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Publication of US9911456B2 publication Critical patent/US9911456B2/en
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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/20—Driving; Starting; Stopping; Control thereof
    • G11B19/2009—Turntables, hubs and motors for disk drives; Mounting of motors in the drive
    • G11B19/2036—Motors characterized by fluid-dynamic bearings
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
    • G11B33/02—Cabinets; Cases; Stands; Disposition of apparatus therein or thereon
    • G11B33/027—Covers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
    • G11B33/14—Reducing influence of physical parameters, e.g. temperature change, moisture, dust
    • G11B33/1446—Reducing contamination, e.g. by dust, debris
    • G11B33/1473—Reducing contamination, e.g. by dust, debris of/from bearings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/27—Rotor cores with permanent magnets
    • H02K1/2786—Outer rotors
    • H02K1/2787—Outer rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
    • H02K1/2789—Outer rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
    • H02K1/2791—Surface mounted magnets; Inset magnets
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K15/00—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines
    • H02K15/02—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
    • H02K15/03—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies having permanent magnets
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/16—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields
    • H02K5/163—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields radially supporting the rotary shaft at only one end of the rotor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/08—Structural association with bearings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/08—Structural association with bearings
    • H02K7/085—Structural association with bearings radially supporting the rotary shaft at only one end of the rotor

Definitions

  • the present invention relates to a spindle motor, a disk drive apparatus, and an insertion method.
  • Hard disk drives typically have spindle motors arranged to rotate disks installed therein.
  • a known hard disk drive and a known spindle motor are described in, for example, JP-A 2006-040423.
  • Paragraph of this publication states that the spindle motor (SPM) is fixed to a base of the hard disk drive (HDD).
  • paragraph of the publication states that a low-density gas having a density lower than that of air, such as, for example, helium, is used as an atmosphere inside a hard disk assembly (HDA).
  • a case of the hard disk drive is arranged to be substantially airtight in order to keep an interior space thereof clean.
  • the low-density gas such as helium
  • the low-density gas tends to easily pass through even a minute gap. Therefore, in the case where an interior of the case is to be filled with the low-density gas as in the case of the hard disk drive described in JP-A 2006-040423, extremely high airtightness is required.
  • it is preferable that the number of through holes defined in a base thereof is decreased.
  • a bearing mechanism arranged to support a rotating portion of the spindle motor is fixed to the base of the hard disk drive.
  • resistance against insertion of the bearing mechanism into the cup portion may be increased because gas cannot be discharged out of the cup portion. This will reduce efficiency in an assembling operation, and make it difficult to accurately position the bearing mechanism with respect to a base member.
  • Preferred embodiments of the present invention provide a technique for reducing resistance when a bearing mechanism is inserted into a cup portion provided in a base member of a spindle motor.
  • a spindle motor including a base member, a bearing mechanism fixed to the base member, and a rotating portion rotatably supported by the bearing mechanism.
  • the base member includes a cup portion including a cylindrical portion arranged to be coaxial or substantially coaxial with a central axis extending in a vertical direction, and a bottom plate portion defined integrally with the cylindrical portion, and arranged to close a lower portion of the cylindrical portion.
  • the bearing mechanism is arranged inside of the cup portion.
  • An outer circumferential surface of the bearing mechanism and an inner circumferential surface of the cylindrical portion have an adhesive layer arranged therebetween.
  • the cup portion includes at least one communicating hole in a vicinity of a junction of the cylindrical portion and the bottom plate portion, the communicating hole passing through the cylindrical portion in a direction that crosses an axial direction.
  • a spindle motor including a base member, a bearing mechanism fixed to the base member, and a rotating portion rotatably supported by the bearing mechanism.
  • the base member includes a cup portion including a cylindrical portion arranged to be coaxial or substantially coaxial with a central axis extending in a vertical direction, and a bottom plate portion defined integrally with the cylindrical portion, and arranged to close a lower portion of the cylindrical portion.
  • the bearing mechanism is arranged inside of the cup portion.
  • An outer circumferential surface of the bearing mechanism and an inner circumferential surface of the cylindrical portion have a first adhesive layer arranged therebetween.
  • the base member includes a communicating hole arranged to pass through the bottom plate portion in an axial direction.
  • the communicating hole has a second adhesive layer arranged therein.
  • a method for inserting a bearing mechanism into a cup portion in a process of manufacturing a spindle motor including a base member including the cup portion, the bearing mechanism fixed to the base member, and a rotating portion rotatably supported by the bearing mechanism.
  • the cup portion includes a cylindrical portion arranged to be coaxial or substantially coaxial with a central axis extending in a vertical direction, and a bottom plate portion defined integrally with the cylindrical portion, and arranged to close a lower portion of the cylindrical portion.
  • the base member further includes a communicating hole arranged to pass through the bottom plate portion in an axial direction.
  • the method includes the steps of inserting a jig into the base member through the communicating hole from below, and causing at least a portion of the jig to pass through the communicating hole; applying a first adhesive to an inner circumferential surface of the cylindrical portion; inserting the bearing mechanism into the cup portion, and bringing at least a portion of the bearing mechanism into contact with at least a portion of the jig; removing the jig from the base member; and applying a second adhesive into the communicating hole.
  • gas which is present between the bearing mechanism and the bottom plate portion is discharged out of the cup portion through the communicating hole when the bearing mechanism is inserted into the cup portion. This leads to a reduction in resistance when the bearing mechanism is inserted into the cup portion.
  • FIG. 1 is a vertical sectional view of a spindle motor according to a first preferred embodiment of the present invention.
  • FIG. 2 is a horizontal sectional view of a cylindrical portion and a bearing mechanism according to the first preferred embodiment of the present invention.
  • FIG. 3 is a vertical sectional view of a disk drive apparatus according to a second preferred embodiment of the present invention.
  • FIG. 4 is a vertical sectional view of a spindle motor according to the second preferred embodiment of the present invention.
  • FIG. 5 is a partial vertical sectional view of a base member according to the second preferred embodiment of the present invention.
  • FIG. 6 is a partial top view of the base member according to the second preferred embodiment of the present invention.
  • FIG. 7 is a partial vertical sectional view of the spindle motor according to the second preferred embodiment of the present invention.
  • FIG. 8 is a diagram illustrating a manner in which the spindle motor according to the second preferred embodiment is manufactured.
  • FIG. 9 is a diagram illustrating a manner in which a communicating hole according to a modification of the second preferred embodiment is bored.
  • FIG. 10 is a vertical sectional view of a spindle motor according to a third preferred embodiment of the present invention.
  • FIG. 11 is a flowchart illustrating a portion of a process of manufacturing the spindle motor according to the third preferred embodiment of the present invention.
  • FIG. 12 is a diagram illustrating a manner in which the spindle motor according to the third preferred embodiment is manufactured.
  • the axial direction is a vertical direction
  • a side on which a bearing mechanism is arranged with respect to a bottom plate portion of a cup portion is an upper side
  • the shape of each member or portion and relative positions of different members or portions will be described based on the above assumptions. Note, however, that the above definitions of the vertical direction and the upper and lower sides are simply made for the sake of convenience in description, and should not be construed to restrict the orientation of a spindle motor or a disk drive apparatus according to any preferred embodiment of the present invention when in use.
  • parallel as used herein includes both “parallel” and “substantially parallel”.
  • perpendicular as used herein includes both “perpendicular” and “substantially perpendicular”.
  • FIG. 1 is a vertical sectional view of a spindle motor 11 A according to a first preferred embodiment of the present invention.
  • the spindle motor 11 A includes a base member 21 A, a bearing mechanism 4 A, and a rotating portion 3 A.
  • the bearing mechanism 4 A is fixed to the base member 21 A.
  • the rotating portion 3 A is rotatably supported by the bearing mechanism 4 A.
  • the base member 21 A includes a bottom plate portion 51 A and a cylindrical portion 52 A.
  • the cylindrical portion 52 A is arranged to be coaxial or substantially coaxial with a central axis 9 A extending in the vertical direction.
  • the bottom plate portion 51 A is arranged to close a lower portion of the cylindrical portion 52 A.
  • the bottom plate portion 51 A and the cylindrical portion 52 A are defined integrally with each other to together define a cup portion 50 A.
  • FIG. 2 is a horizontal sectional view of the cylindrical portion 52 A and the bearing mechanism 4 A.
  • the bearing mechanism 4 A is arranged inside of the cup portion 50 A.
  • an adhesive layer 73 A is arranged between an outer circumferential surface of the bearing mechanism 4 A and an inner circumferential surface of the cylindrical portion 52 A. The bearing mechanism 4 A is thus fixed to the cylindrical portion 52 A.
  • the cup portion 50 A includes a first communicating hole 71 A, which is not filled with the adhesive layer 73 A, in the vicinity of a junction of the cylindrical portion 52 A and the bottom plate portion 51 A.
  • the first communicating hole 71 A is arranged to pass through the cylindrical portion 52 A in a radial direction that crosses the axial direction.
  • the bearing mechanism 4 A When the spindle motor 11 A is manufactured, the bearing mechanism 4 A is inserted inside the cylindrical portion 52 A of the cup portion 50 A. At this time, gas which is present between the bearing mechanism 4 A and the bottom plate portion 51 A travels through the first communicating hole 71 A to be discharged out of the cup portion 50 A. This leads to a reduction in resistance when the bearing mechanism 4 A is inserted into the cup portion 50 A, and enables the bearing mechanism 4 A to be smoothly inserted into the cup portion 50 A.
  • At least a portion of an opening portion of the first communicating hole 71 A defined in the inner circumferential surface of the cylindrical portion 52 A is arranged below the bearing mechanism 4 A. This arrangement contributes to preventing an adhesive in a gap between the cup portion 50 A and the bearing mechanism 4 A from entering into the first communicating hole 71 A when the bearing mechanism 4 A is inserted and the adhesive is pushed out downwardly.
  • the first communicating hole 71 A may be arranged to extend from an inner side to an outer side of the cylindrical portion 52 A at a constant height, i.e., at a constant axial position, as illustrated in FIG. 1 , or may alternatively be arranged to extend obliquely such that the axial position of the first communicating hole 71 A becomes higher as the first communicating hole 71 A extends from the inner side toward the outer side of the cylindrical portion 52 A (see FIG. 4 ).
  • the first communicating hole 71 A is arranged to extend at a constant height, the length of the first communicating hole 71 A can be minimized, resulting in reduced channel resistance.
  • a portion of the base member 21 A which is radially outside of the cylindrical portion 52 A can be arranged to have a thickness greater than that of the bottom plate portion 51 A. This allows the first communicating hole 71 A to be defined while maintaining rigidity of the base member 21 A.
  • Each of the opening portion of the first communicating hole 71 A defined in the inner circumferential surface of the cylindrical portion 52 A, and an opening portion of the first communicating hole 71 A defined in an outer circumferential surface of the cylindrical portion 52 A may be circular, elliptical, square, rectangular, in the shape of a polygon other than a square or rectangle, or in any other desirable shape.
  • the opening portion is circular, the size of the hole defined in the cup portion 50 A can be minimized, allowing rigidity of the cup portion 50 A to be maintained.
  • FIG. 3 is a vertical sectional view of a disk drive apparatus 1 according to a second preferred embodiment of the present invention.
  • the disk drive apparatus 1 is an apparatus arranged to perform reading and writing of information from or to magnetic disks 12 while rotating the magnetic disks 12 .
  • the disk drive apparatus 1 includes a spindle motor 11 , the magnetic disks 12 , which are three in number, an access portion 13 , and a cover 14 .
  • the spindle motor 11 is arranged to rotate the three magnetic disks 12 about a central axis 9 while supporting the magnetic disks 12 .
  • the spindle motor 11 includes a base member 21 arranged to extend radially on a lower side of the magnetic disks 12 .
  • a rotating portion 3 of the spindle motor 11 , the three magnetic disks 12 , and the access portion 13 are housed in a case defined by the base member 21 and the cover 14 .
  • the access portion 13 is arranged to move heads 131 along recording surfaces of the magnetic disks 12 to perform the reading and the writing of information from or to the magnetic disks 12 .
  • a junction of the base member 21 and the cover 14 is sealed by a sealant, such as, for example, an elastomer.
  • a sealant such as, for example, an elastomer.
  • An interior space of the case is thus kept airtight.
  • the interior of the case is filled with a clean air containing few particles.
  • the interior of the case may be filled with helium, hydrogen, a gas mixture of helium and hydrogen, or a gas mixture of any one of the above and air, instead of the air. This leads to a reduction in resistance of gas against the access portion 13 .
  • the disk drive apparatus 1 may alternatively be arranged to include one, two, or more than three magnetic disks 12 .
  • the access portion 13 may alternatively be arranged to perform only one of the reading and the writing of information from or to the magnetic disk(s) 12 .
  • FIG. 4 is a vertical sectional view of the spindle motor 11 .
  • the spindle motor 11 includes a stationary portion 2 and the rotating portion 3 .
  • the stationary portion 2 is arranged to be stationary relative to both the base member 21 and the cover 14 .
  • the rotating portion 3 is supported to be rotatable with respect to the stationary portion 2 .
  • the stationary portion 2 includes the base member 21 , an armature 22 , a sleeve 23 , and a cap 24 .
  • the base member 21 is arranged to support both the armature 22 and the sleeve 23 .
  • the base member 21 is a metal member, and is obtained, for example, by casting.
  • the base member 21 is made of, for example, a metal material, such as an aluminum alloy.
  • the base member 21 includes an inner bottom plate portion 51 , a cylindrical portion 52 , and an outer bottom plate portion 53 .
  • the inner bottom plate portion 51 , the cylindrical portion 52 , and the outer bottom plate portion 53 are defined integrally with one another.
  • the inner bottom plate portion 51 is arranged to extend perpendicularly to the central axis 9 on a lower side of the sleeve 23 and the cap 24 to substantially assume the shape of a disk.
  • the cylindrical portion 52 is arranged to extend upward from a radially outer edge portion of the inner bottom plate portion 51 to substantially assume the shape of a cylinder.
  • the cylindrical portion 52 is arranged to be coaxial or substantially coaxial with the central axis 9 .
  • the inner bottom plate portion 51 is arranged to close a lower portion of the cylindrical portion 52 . That is, the inner bottom plate portion 51 and the cylindrical portion 52 are arranged to together define a cup portion 50 having a bottom and being substantially cylindrical.
  • the outer bottom plate portion 53 is arranged to extend further radially outward from the radially outer edge portion of the inner bottom plate portion 51 .
  • the armature 22 includes a stator core 61 and a plurality of coils 62 .
  • the stator core 61 is defined, for example, by laminated steel sheets.
  • the laminated steel sheets are preferably a collection of electromagnetic steel sheets placed one upon another in the axial direction.
  • a silicon steel sheet or the like, for example, is used as each of the electromagnetic steel sheets.
  • the stator core 61 includes an annular core back 611 and a plurality of teeth 612 arranged to project radially outward from the core back 611 .
  • the core back 611 is fixed to an outer circumferential surface of the cylindrical portion 52 .
  • the teeth 612 are arranged at substantially regular intervals in the circumferential direction.
  • Each of the coils 62 is defined by a conducting wire wound around a separate one of the teeth 612 .
  • the sleeve 23 is arranged to extend in the axial direction to assume a substantially cylindrical shape around a shaft 31 , which will be described below.
  • a lower portion of the sleeve 23 is arranged inside of the cup portion 50 . That is, the sleeve 23 is arranged radially inside of the cylindrical portion 52 and above the inner bottom plate portion 51 .
  • An outer circumferential surface of the sleeve 23 is fixed to an inner circumferential surface of the cylindrical portion 52 through an adhesive layer 73 , which will be described below.
  • An inner circumferential surface of the sleeve 23 is arranged radially opposite to an outer circumferential surface of the shaft 31 .
  • a lower opening of the sleeve 23 is closed by the cap 24 .
  • the rotating portion 3 includes the shaft 31 , a hub 32 , a back yoke 33 , and a magnet 34 .
  • the shaft 31 is arranged to extend in the axial direction radially inside of the sleeve 23 .
  • a metal such as stainless steel, for example, is used as a material of the shaft 31 .
  • An upper end portion of the shaft 31 is arranged to project upward above an upper surface of the sleeve 23 .
  • the shaft 31 includes a plate portion 311 arranged to project radially outward from a lower end portion thereof. An upper surface of the plate portion 311 is arranged axially opposite to the sleeve 23 . Upward coming off of the shaft 31 is thus prevented.
  • a lubricating fluid 41 is arranged between the shaft 31 and a combination of the sleeve 23 and the cap 24 .
  • a surface of the lubricating fluid 41 is defined between the inner circumferential surface of the sleeve 23 and the outer circumferential surface of the shaft 31 .
  • the shaft 31 is supported through the lubricating fluid 41 to be rotatable with respect to the sleeve 23 and the cap 24 . That is, in the present preferred embodiment, a bearing mechanism 4 is defined by the combination of the sleeve 23 and the cap 24 , both of which belong to the stationary portion 2 , the shaft 31 , which belongs to the rotating portion 3 , and the lubricating fluid 41 arranged therebetween.
  • a polyolester oil or a diester oil, for example, is used as the lubricating fluid 41 .
  • the hub 32 includes a top plate portion 321 , an annular wall portion 322 , and a flange portion 323 .
  • the top plate portion 321 is arranged to cover an upper side of the armature 22 and the sleeve 23 .
  • An inner circumferential surface of the top plate portion 321 is fixed to the upper end portion of the shaft 31 .
  • the annular wall portion 322 is arranged to extend downward from a radially outer edge portion of the top plate portion 321 to substantially assume the shape of a cylinder.
  • the flange portion 323 is arranged to project radially outward from a lower end portion of the annular wall portion 322 .
  • the hub 32 is arranged to support the three magnetic disks 12 . At least a portion of an inner circumferential portion of each magnetic disk 12 is arranged to be in contact with an outer circumferential surface of the annular wall portion 322 . Each magnetic disk 12 is thus radially positioned. In addition, at least a portion of a lower surface of a lowermost one of the magnetic disks 12 is arranged to be in contact with an upper surface of the flange portion 323 . The lowermost magnetic disk 12 is thus axially positioned.
  • the back yoke 33 is an annular member made of a magnetic material.
  • the back yoke 33 is fixed to each of a lower surface of the top plate portion 321 and an inner circumferential surface of the annular wall portion 322 through, for example, an adhesive layer.
  • the magnet 34 which is annular in shape, is fixed to an inner circumferential surface of the back yoke 33 through, for example, an adhesive layer.
  • An inner circumferential surface of the magnet 34 is arranged radially opposite to a radially outer end surface of each of the teeth 612 .
  • the inner circumferential surface of the magnet 34 includes north and south poles arranged to alternate with each other in the circumferential direction.
  • a plurality of magnets may be used.
  • the magnets are arranged in the circumferential direction such that north and south poles alternate with each other.
  • FIG. 5 is a partial vertical sectional view of the base member 21 .
  • FIG. 6 is a partial top view of the base member 21 .
  • the base member 21 includes the cup portion 50 having the bottom and being substantially cylindrical and which is defined by the inner bottom plate portion 51 and the cylindrical portion 52 .
  • the base member 21 includes a first communicating hole 71 , which is not filled with an adhesive, in the vicinity of a junction of the cylindrical portion 52 and the inner bottom plate portion 51 .
  • the first communicating hole 71 is arranged to extend from the inner circumferential surface to the outer circumferential surface of the cylindrical portion 52 .
  • the first communicating hole 71 is arranged to pass through the cylindrical portion 52 in a direction that crosses the axial direction.
  • the first communicating hole 71 may be arranged to extend from an inner side to an outer side of the cylindrical portion 52 at a constant height, i.e., at a constant axial position, or may alternatively be arranged to extend obliquely such that the axial position of the first communicating hole 71 becomes higher as the first communicating hole 71 extends from the inner side toward the outer side of the cylindrical portion 52 .
  • the number of first communicating holes 71 may be either one or more than one.
  • the first communicating hole 71 is defined by, for example, inserting a columnar drill into the base member 21 .
  • FIG. 7 is a partial vertical sectional view of the spindle motor 11 .
  • the adhesive layer 73 is arranged between the outer circumferential surface of the sleeve 23 and the inner circumferential surface of the cylindrical portion 52 .
  • the cylindrical portion 52 and the sleeve 23 are thus fixed to each other.
  • An epoxy resin adhesive for example, is used as an adhesive that defines the adhesive layer 73 .
  • an electrically conductive adhesive 75 which is different in type from the adhesive of the adhesive layer 73 , is arranged between the outer circumferential surface of the sleeve 23 and an inner circumferential surface of a portion of the cylindrical portion 52 which is in the vicinity of an upper end portion of the cylindrical portion 52 .
  • An electric charge generated in the rotating portion 3 flows to the base member 21 through the lubricating fluid 41 , the sleeve 23 , and the electrically conductive adhesive 75 . The rotating portion 3 is thus prevented from being electrified.
  • the electrically conductive adhesive 75 may alternatively be arranged between the outer circumferential surface of the sleeve 23 and an inner circumferential surface of a portion of the cylindrical portion 52 which is in the vicinity of a lower end portion of the cylindrical portion 52 .
  • a combination of a lower end portion of the sleeve 23 and a lower surface of the cap 24 is arranged axially opposite to an upper surface of the inner bottom plate portion 51 with a gap 76 therebetween.
  • the base member 21 includes, in the inner circumferential surface of the cylindrical portion 52 , an inner circumferential groove 77 arranged to extend in the circumferential direction.
  • the radial distance between the outer circumferential surface of the sleeve 23 and a curved surface which defines the inner circumferential groove 77 is greater than the radial distance between the outer circumferential surface of the sleeve 23 and a remaining portion of the inner circumferential surface of the cylindrical portion 52 , excluding the inner circumferential groove 77 .
  • the inner circumferential groove 77 and an area 60 of contact between the cylindrical portion 52 and the stator core 61 are arranged to overlap with each other in the radial direction. This makes it more unlikely for a radially inward stress which the cylindrical portion 52 receives through the contact area 60 to be transmitted to the sleeve 23 . This reduces the likelihood of distortion of the sleeve 23 .
  • FIG. 8 is a vertical sectional view illustrating a manner in which the bearing mechanism 4 is fitted to the cup portion 50 of the base member 21 .
  • an adhesive 730 and the electrically conductive adhesive 75 are first applied to the inner circumferential surface of the cylindrical portion 52 .
  • the electrically conductive adhesive 75 is applied to the inner circumferential surface of the portion of the cylindrical portion 52 which is in the vicinity of the upper end portion of the cylindrical portion 52 .
  • the adhesive 730 is applied to a position below the electrically conductive adhesive 75 such that the adhesive 730 is arranged to extend in the shape of a circular arc in the circumferential direction.
  • the bearing mechanism 4 is inserted into the cup portion 50 from above the cup portion 50 as indicated by a white arrow in FIG.
  • each of the adhesive 730 and the electrically conductive adhesive 75 is arranged between the inner circumferential surface of the cylindrical portion 52 and the outer circumferential surface of the sleeve 23 , that is, between the inner circumferential surface of the cylindrical portion 52 and an outer circumferential surface of the bearing mechanism 4 .
  • the insertion of the bearing mechanism 4 causes the adhesive 730 to spread downward. Then, the adhesive 730 is cured between the sleeve 23 and the cylindrical portion 52 to define the adhesive layer 73 .
  • At least a portion of an opening portion of the first communicating hole 71 defined in the inner circumferential surface of the cylindrical portion 52 is arranged below the bearing mechanism 4 . That is, this opening portion of the first communicating hole 71 is defined at such an axial position that the opening portion faces on the gap 76 between the bearing mechanism 4 and the inner bottom plate portion 51 after the bearing mechanism 4 is inserted into the cup portion 50 . Therefore, even if the adhesive layer 73 is spread up to the vicinity of the lower end portion of the cylindrical portion 52 at the time of the insertion of the bearing mechanism 4 , it is unlikely that the opening portion of the first communicating hole 71 will be completely sealed with the adhesive layer 73 . Therefore, the gas which is present between the bearing mechanism 4 and the inner bottom plate portion 51 can be discharged more securely.
  • the gap 76 between the bearing mechanism 4 and the inner bottom plate portion 51 is in communication with an outside of the cup portion 50 through the first communicating hole 71 . Therefore, a change in ambient temperature would not easily cause a change in pressure in the gap 76 . Therefore, neither the sleeve 23 nor the cap 24 tends to easily get distorted due to a pressure.
  • the electrically conductive adhesive 75 is applied to a position, on the inner circumferential surface of the cylindrical portion 52 , which does not overlap with the first communicating hole 71 .
  • This arrangement makes it unlikely for the electrically conductive adhesive 75 to enter into the first communicating hole 71 .
  • the electrically conductive adhesive 75 is arranged at a circumferential position opposite to that of the first communicating hole 71 in a plan view. This arrangement further reduces the likelihood that the electrically conductive adhesive 75 will enter into the first communicating hole 71 .
  • each of a wall surface of the first communicating hole 71 and a surface of the base member 21 is coated with an electrodeposition coating film.
  • a metal surface of the aluminum alloy is exposed on the inner circumferential surface of the cylindrical portion 52 .
  • the adhesive layer 73 is adhered more easily than to a surface of the electrodeposition coating film. This makes it easier for the adhesive layer 73 to be held between the inner circumferential surface of the cylindrical portion 52 and the outer circumferential surface of the sleeve 23 . This contributes to more secure adhesion between the cylindrical portion 52 and the sleeve 23 .
  • electrodeposition coating is first applied to the entire surface of the base member 21 , for example, and thereafter the inner circumferential surface of the cylindrical portion 52 is subjected to a cutting process.
  • This method allows the metal surface to be exposed on the inner circumferential surface of the cylindrical portion 52 while leaving the electrodeposition coating film on the wall surface of the first communicating hole 71 and the remaining surface of the base member 21 .
  • FIG. 9 is a top view illustrating a manner in which a first communicating hole 71 B according to a modification of the second preferred embodiment is bored.
  • a cutting tool 78 B including a circular blade may be brought closer to a cylindrical portion 52 B in a radial direction (i.e., a boring direction 82 B) while being rotated to bore the first communicating hole 71 B.
  • both circumferential edges of the first communicating hole 71 B will each be in the shape of a circular arc.
  • an increase in an opening area of the first communicating hole 71 B can be achieved, leading to reduced channel resistance for gas in the first communicating hole 71 B. This leads to an additional reduction in resistance when a bearing mechanism 4 B is inserted into a cup portion.
  • FIG. 10 is a vertical sectional view of a spindle motor 11 C according to a third preferred embodiment of the present invention.
  • the spindle motor 11 C according to the third preferred embodiment will now be described below with focus on differences from the spindle motor 11 according to the second preferred embodiment. Redundant descriptions of features of the third preferred embodiment which are shared by the second preferred embodiment will be omitted.
  • the spindle motor 11 C according to the present preferred embodiment is different from the spindle motor 11 according to the second preferred embodiment in that an inner bottom plate portion 51 C of a base member 21 C further includes two second communicating holes 74 C each of which is arranged to pass through the inner bottom plate portion 51 C in the axial direction.
  • the second communicating holes 74 C may be provided either in addition to a first communicating hole 71 C or in place of the first communicating hole 71 C.
  • FIG. 11 is a flowchart illustrating a portion of a process of manufacturing the spindle motor 11 C.
  • FIG. 12 is a diagram illustrating a manner in which the spindle motor 11 C is manufactured. As illustrated in FIGS. 11 and 12 , when the spindle motor 11 C is manufactured, the bearing mechanism 4 C with a shaft 31 C and a hub 32 C attached thereto is inserted into the cup portion 50 C in a direction indicated by a white arrow in FIG. 12 . In addition, in a previous step, a jig 80 C is inserted from below into the base member 21 C through the second communicating holes 74 C in advance.
  • At least a portion of the jig 80 C is passed through each second communicating hole 74 C to reach a space inside of the cylindrical portion 52 C. Then, a lower end of the bearing mechanism 4 C with the shaft 31 C and the hub 32 C attached thereto is brought into contact with an upper end of the jig 80 C. In this situation, the height of the hub 32 C is adjusted while a lower surface of the shaft 31 C and a cap 24 C are pressed against each other. The bearing mechanism 4 C can thus be positioned accurately.
  • each second communicating hole 74 C is preferably arranged radially outward of the shaft 31 C, which is rotatably supported by the bearing mechanism 4 C.
  • the bearing mechanism 4 C can be stably supported by the jig 80 C when the second communicating holes 74 C are arranged radially outward. Accordingly, the height of the hub 32 can be adjusted with increased efficiency.
  • the jig 80 C is first inserted from below into the base member 21 C through the second communicating holes 74 C (step S 1 ). At least a portion of the jig 80 C is thus passed through each second communicating hole 74 C to be placed inside of the cylindrical portion 52 C.
  • a first adhesive 730 C is applied to an inner circumferential surface of the cylindrical portion 52 C (step S 2 ).
  • the bearing mechanism 4 C with the shaft 31 C and the hub 32 C attached thereto is inserted into the cup portion 50 C (step S 3 ).
  • the lower end of the bearing mechanism 4 C is brought into contact with the upper end of the jig 80 C.
  • the height of the hub 32 C is adjusted while the lower surface of the shaft 31 C and the cap 24 C are pressed against each other.
  • the bearing mechanism 4 C is positioned accurately.
  • the first adhesive 730 C is cured between a sleeve 23 C and the cylindrical portion 52 C to define a first adhesive layer 73 C.
  • each second communicating hole 74 C is sealed therewith.
  • the base member 21 C preferably includes a tapered surface 81 C which increases in diameter with decreasing height at a lower end of each second communicating hole 74 C. This allows the second adhesive layer 79 C to be easily held at an opening portion of the second communicating hole 74 C at the lower end thereof. Moreover, the insertion of the jig 80 C into the second communicating holes 74 C is made easier.
  • each of a wall surface of each second communicating hole 74 C and a surface of the base member 21 C is coated with an electrodeposition coating film. Meanwhile, a metal surface of an aluminum alloy is exposed on the inner circumferential surface of the cylindrical portion 52 C. To this metal surface, the first adhesive layer 73 C is adhered more easily than to a surface of the electrodeposition coating film. This makes it easier for the first adhesive layer 73 C to be held between the inner circumferential surface of the cylindrical portion 52 C and an outer circumferential surface of the sleeve 23 C. This contributes to more secure adhesion between the cylindrical portion 52 C and the sleeve 23 C.
  • the adhesive that defines the adhesive layer is not limited to the epoxy resin adhesive, but may alternatively be, for example, an acrylic resin adhesive or the like. Note, however, that the adhesive that defines the adhesive layer is preferably an adhesive which has at least one property among a thermosetting property, an anaerobic setting property, and a UV-curing property.
  • the sleeve included in the bearing mechanism may not necessarily be defined by a single member, but may alternatively be defined by a plurality of members.
  • the sleeve may be defined by two members, a sleeve housing and a sleeve body arranged inside of the sleeve housing.
  • the outer circumferential surface of the bearing mechanism refers to an outer circumferential surface of the sleeve housing.
  • the sleeve may alternatively be defined by three or more members.
  • Preferred embodiments of the present invention are applicable to spindle motors and disk drive apparatuses.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Motor Or Generator Frames (AREA)
  • Rotational Drive Of Disk (AREA)
  • Mounting Of Bearings Or Others (AREA)
  • Sliding-Contact Bearings (AREA)
US15/438,953 2016-02-25 2017-02-22 Spindle motor and disk drive apparatus Expired - Fee Related US9911456B2 (en)

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JP2016034377A JP6690295B2 (ja) 2016-02-25 2016-02-25 スピンドルモータ、ディスク駆動装置、および挿入方法
JP2016-034377 2016-02-25

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US10923996B2 (en) * 2018-10-17 2021-02-16 Chun-Jong Chang DC motor-dynamo
CN113677187A (zh) * 2019-03-28 2021-11-19 渥美不动产有限公司 具备圆柱形旋转体的作业装置
CN113364240A (zh) * 2021-04-28 2021-09-07 宁波赛嘉机电有限公司 外转子电机及其装配方法

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CN206471961U (zh) 2017-09-05
US10102876B2 (en) 2018-10-16
JP2017150592A (ja) 2017-08-31
US20180090166A1 (en) 2018-03-29
US20170249968A1 (en) 2017-08-31
JP6690295B2 (ja) 2020-04-28

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